File upstream PRs to fix dependency review for Rust crates

[ibeckermayer]

In 6b2be07 we added some overrides for our license check, based on the failures in https://github.com/gravitational/teleport/actions/runs/7280939099/job/19840691057?pr=26874

Let's file upstream PRs to fix the license field in these repos so that the SPDX parser can comprehend it. (ring is an exception due to its non-standard license, that will need to remain an override and should be reviewed by legal.)

Tasks

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1. Updates license field to valid SPDX format rusticata/asn1-rs#34
   +0
2. Updates license field to valid SPDX format rusticata/der-parser#70
   +0
3. Updates license field to valid SPDX format dalek-cryptography/curve25519-dalek#647
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4. chore: update license field to valid SPDX format Devolutions/sspi-rs#225
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5. Updates license field to valid SPDX format cloudflare/boring#230
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6. ring review by legal